title: Comparative transcriptome analysis between somatic embryos (SEs) and zygotic embryos in cotton: evidence for stress response functions in SE development.
abstract: As a product of asexual reproduction in plants, the somatic embryo (SE) differentiates into a new plantlet via a zygotic embryogenesis-like process. Here, we present the phenotypic and cellular differences between SEs and zygotic embryos (ZEs) revealed by histological section scanning using three parallel development stages of the two types of embryos of cotton (Gossypium hirsutum cv. YZ1), including globular, torpedo and cotyledonary-stages. To identify the molecular characteristics of SE development in cotton, the digital gene expression system was used to profile the genes active during SE and ZE development. A total of 4242 differentially expressed genes (DEGs) were identified in at least one developmental stage. Expression pattern and functional classification analysis based on these DEGs reveals that SE development exhibits a transcriptional activation of stress responses. RT-PCR analysis further confirmed enhanced expression levels of stress-related genes in SEs than in ZEs. Experimental stress treatment, induced by NaCl and ABA, accelerated SE development and increased the transcription of genes related to stress response, in parallel with decelerated proliferation of embryogenic calluses under stress treatment. Our data reveal that SE development involves the activation of stress responses, which we suggest may regulate the balance between cell proliferation and differentiation. These results provide new insight into the molecular mechanisms of SE development and suggest strategies that can be used for regulating the developmental processes of somatic embryogenesis.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Fangyan
authors.initials: F
authors.lastname: Jin
authors.forename: Lisong
authors.initials: L
authors.lastname: Hu
authors.forename: Daojun
authors.initials: D
authors.lastname: Yuan
authors.forename: Jiao
authors.initials: J
authors.lastname: Xu
authors.forename: Wenhui
authors.initials: W
authors.lastname: Gao
authors.forename: Liangrong
authors.initials: L
authors.lastname: He
authors.forename: Xiyan
authors.initials: X
authors.lastname: Yang
authors.forename: Xianlong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D001483:Base Sequence; D002454:Cell Differentiation; D049109:Cell Proliferation; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D063990:Gene Ontology; D003368:Gossypium / Q000166:cytology / Q000196:embryology / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D058439:Plant Somatic Embryogenesis Techniques; D012639:Seeds / Q000166:cytology / Q000196:embryology / Q000235:genetics; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D013312:Stress, Physiological; D059467:Transcriptome
chemical_list: D010940:Plant Proteins
keywords: Gossypium hirsutum; embryo development; somatic embryo; stress response gene; transcriptional profiling; zygotic embryo